This invention relates generally to a spraying apparatus valve assembly for delivering a component mixture to the spraying nozzle of a spraying device and more particularly relates to a valve assembly and spraying apparatus for mixing and spraying a uniform blend of two or more components.
In the art of devices spraying polyester resins and catalysts to a surface, many methods and processes have been developed over the past years. These devices have been successful to some extent, but they have not been satisfactory for hand-held use in that they have been typically heavy and cumbersome to use. In addition, they are generally very complicated and require extensive maintenance work and care.
In this particular field, it has been a generally accepted practice to apply polyester resins and catalysts via a resin pump, catalyst or injector pump, and an air source to the gun and blend together by internal mixing in the gun nozzle head or external mixing at the surface being coated. In the art of spraying two different methods have emerged. One is low-pressure (under 100 psi) termed "air-atomized" process internally mixed at the gun nozzle in which the catalyst arrives at the gun body from an air atomized injector providing pre-mixed catalyst and air to the gun. The pre-mixed catalyst and air is carried to the gun via suitable hose in an atomized state. The resin and atomized catalysts are then internally mixed through a grid arrangement in the nozzle section of the spray gun. This method requires a purging of all passages including nozzle and body after each use.
The second method uses high pressures and is generally termed "airless". In this system polyester resin is pumped to the spray gun and through an orifice or airless V-jet in the gun nozzle head. Catalyst is also pumped to the nozzle and remains in an airless state, and in some instances requires dilution with a compatible agent. Diluted catalyst allows the use of orifices or V-jets of sufficient size to avoid the frequent problem of plug-ups coming from small particles. The nozzle head has two or more V-jet arrangements to form the necessary spray pattern. The V-jets in the nozzle are directed at an angle toward each other allowing the catalyst and resin to intersect forming a proper spray pattern. In addition to the disadvantages already mentioned, such as high-pressure plug-ups on the nozzle V-jets, the prior art system requires extensive maintenance in order to keep them in suitable condition for continuous use. This requires frequent cleaning in order to prevent hardening of material clogging the passageways. Thus, there is a great need for simplicity of design to reduce maintenance costs and increase the usability of this prior art system.
Also valves for use in spraying devices to mix components for delivery to spray nozzles are known in the art. However, they have not always been satisfactory and in the case of spraying devices for mixing a catalyst with a resin they have been particularly experiencing difficulties. For the latter purpose the present valves mix air with the catalyst for delivery to a nozzle and simultaneous spraying with a resin. However, it has been difficult to obtain a proper mixture of air and catalyst for combination with the resin to produce the desired result. One such prior art device has a dual-valve arrangement in which the air moves a body away from a second orifice permitting the catalyst to mix with the air. While this valve arrangement has achieved some success, it is not suitable for low-pressure requirements because the valve body tends to chatter or vibrate. The present invention solves the problems of prior valves and provides a smooth, easily controlled mixing assembly.